Abstract

There continues to be debate about the long-term neuropsychological
impact of mild traumatic brain injury (MTBI). A meta-analysis of the
relevant literature was conducted to determine the impact of MTBI across
nine cognitive domains. The analysis was based on 39 studies involving
1463 cases of MTBI and 1191 control cases. The overall effect of MTBI on
neuropsychological functioning was moderate (d = .54). However,
findings were moderated by cognitive domain, time since injury, patient
characteristics, and sampling methods. Acute effects (less than 3 months
postinjury) of MTBI were greatest for delayed memory and fluency
(d = 1.03 and .89, respectively). In unselected or prospective
samples, the overall analysis revealed no residual neuropsychological
impairment by 3 months postinjury (d = .04). In contrast,
clinic-based samples and samples including participants in litigation were
associated with greater cognitive sequelae of MTBI (d = .74 and
.78, respectively at 3 months or greater). Indeed, litigation was
associated with stable or worsening of cognitive functioning over time.
The implications and limitations of these findings are discussed.
(JINS, 2005, 11, 215–227.)

(Received July 8 2004)(Revised November 26 2004)(Accepted December 21 2004)